Method of and apparatus for eliminating disturbing effects



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rafisma? April 22 1924. 1,491,543

- I A. MEISSNER METHOD OF AND APPARATUS FOR ELIMINATING DISTURBING EFFECTS Filed May 5 1922 I Jwumtow AL ANDER MEISSNER UNITED STATES draft PATENT OFFICE.

ALEXANDER MEISSNER, OF BERLIN, GERMANY, ASSIGNOR TO GESELLSCHAFT FU'R DRAHTLOSE TELEGRAPHIE M. B. H. HALLESCHES, 0F BERLIN, GERMANY, A CO'R- PORATION OF GERMANY.

METHOD OF AND APPARATUS FOR ELIMINATING DISTURBING- EFFECTS.

Application filed. May 8, 1922. Serial No. 558,801.

To all whom it may concern:

Be it known that I, ALEXANDER MEISSNER, a citizen of Germany, and residing at Berlin, Germany, have invented certain new and useful Improvements in Methods of and Apparatus for Eliminating Disturbing Effects, on which an application for Letters Patent was filed in Germany April 15, 1921, and of which the following is a specification.

This invention relates to arrangements for eliminating disturbing effects when receiving messages in wireless telegraph and telephone stations equipped with two receiving systems and a compensating or neutnalizing arrangement for the disturbing currents.

Arrangements for eliminating disturbing efiects in wireless telegraphy and telephony are known in which tworeceiving systems or circuits are used that are tuned for different Wave lengths and the energies that would produce disturbing efi'ects are neutralized, as in an indicator system or circuit, for example, while the useful energy that produces the signals is unequally distributed in the two receiving systems and is therefore not neutralized. According to the particular form of circuit arrangement adopted two entirely separate aerials were used, or only one aerial with two branches or two secondary systems was employed.

In the arrangement according to this invention, two receiving systems are employed also, but contrary to the known arrangements these systems are tuned forthe same, or approximately the same, wave length. A primary advantage thus obtained is that the disturbing currents are completely neutralized, a result which is not accomplished in the use of known arrangements because their wave lengths of the received energy differs in their two receiving systems. In order that the useful energy, i. e., the ener destined to produce the intelligible soun s, that is taken in by the two receiving systems may not be neutralized, it is transformed in different ways in the two systems. When a common indicator circuit or system in which the neutralizing efl'ect takes place is used, the circuits that carry the detector currents are arrangedin such a manner that the disturbing currents act in opposite senses and neutralize each other, while the useful energy takes effect in the apparatus, such as a telephonic receiver, that it is destined to operate. The arrangement may be employed both for receiving damped and undamped oscillations. The two receiving systefiis may consist of two separate aerials or aerial branches, or, if only one aerial is employed, they may consist of two secondary receiving circuits coupled independently to the aerial, while in known arrangements for eliminating disturbances only the one or the other of these means can be used. In the novel arrangement according to the invention atmospheric disturbances are eliminated entirely, and extraneous disturbing sounds can alsobe sup-pressed, In particular, disturbances that produce singing notes can be eliminated when receiving undamped oscillations.

The invention is shown by .way of example in the accompanying drawing in which- Fig. 1 shows an arrangement with two aerials, and

Fig. 2 an arrangement with one aerial and two secondary systems coupled therewith.

The two receiving aerials 1 and 2 of Fig. 1 are coupled with secondary circuits 3 and 4; respectively, and both aerials with their secondary circuits are tuned to receive waves of the same frequency.

A superimposing arrangement acts through the coil 5 on the receiving system 1,3 so that a tone of a certain frequency, for

example, of 1000, is produced in the transformer 6 of the audion detector in the circuit 3. A second superimposing arrangement acts through a coil 7 on the receiving system 2,4 so as to give rise to a different interfering tone frequency, for example, 500,

in the transformer 8 of the audion detector in the circuit 4. The currents of the two audion detector circuits then act together eitherin parallel or in series on a receiver 9 or some other suitable form of indicator, the secondary or receiver windings of the transformers 6 and 8 being connected to the do tector circuits 3 and 4 in such a manner that disturbing influences neutralize each other. As currents of different frequencies (1000 and 500 in the case assumed above) flow in the two windings, the currents which produce the useful effects do not neutralize each other, but produce a mixed tone in the telephone receiver. The disturbing currents or effects however are completely eliminated.

Atmospheric disturbances have no distinct time period of vibration, being very highly damped, and, consequently, produce little or no beats with the superimposing arrangements 5 and 7, so that the currents due to atmospheric or static impulses may be made equal and opposite and may therefore, be readily neutralized. The superimposing arrangements 5 and 7 act to produce beats only with the portion of the received energy which has a distinct time period of vibration, such as the signaling energy.

Another method, which is not quite so efficient, but which may also be employed in accordance with the invention, consists in not superimposing currents in the receiving system 2,4, but only in the receiving sys tem 1,3. Currents which produce a useful effect will, in such cases, not pass through 2,4, but only through 1,3; or in receiving waves that produce musical notes normal musical sounds will be received through 2,4, while converted notes will be sent by means of superimposed currents through 1,3. In cases in which the amplitudes in the two systems differ from each other amplifiers may be interposed in the circuit. In receiving musical notes the arrangement may also be such that the tone in the one system is destroyed by superimposed currents, while in the other system the musical note remains.

In the arrangement shown in Fig. 2 the two secondary circuits 3 and 4 are coupled to the aerial 1 and superimposing arrangements are arranged to operate on the circuits 3 and 4 through the coils 5 and 7. The telephone receiver may be connected to the two transformers 6 and 8 as in Fig. 1.

The conversion of the useful energy in the use of the arrangement shown in Fig. 2 may be arranged to take place as follows. If, for example, oscillations of 100,000 cycles per second are being received, the frequency superimposed on the receiving circuit 3 may be 90000, while that superimposed upon the other receiving circuit 4 may be 91000 periods. The mutual induction of the su perimposing arrangement 5 in the receiving circuit 3 and of the superimposing arrangement 7 in the circuit 4 (Fig. 2) can be eliminated by compensation or neutralization. The result of the two superimposed effects is that a periodicity of 10,000 is obtained in the transformer 6, while a periodicity of 9,000 is obtained in the transformer 8. In the system lying on the secondary side 2.

balancing circuit arrangement is employed to cause disturbing influences to neutralize each other, as above explained in connection with the arrangement of Fig. 1. The received signaling currents are not neutralized in spite of the balancing or compensating effects of the system, for in the receiver device consisting of the valve 10 and the telephone receiver 9 connected with the circuit of the transformers 6 and 8, a differential tone of a frequency of 1000 will result from the two frequencies 10000 and 9000. Here again it is possible to differentiate the receiving circuit 3 from the circuit 4 by simply omitting the superimposing arrange ment from the system 4. In such a case it will be advantageous to employ another superimposed current of a frequency of 10,000 in the circuit 6,8. A differential tone will then again be obtained in the receiver. This arrangement will admit of a great number of variations particularly if the indicator used for receiving consists of a recording device instead of a telephone receiver.

I claim:

1. The method of receiving signals and eliminating disturbances in radio receiving systems which consists in receiving energy as two effects having substantially the same frequency and each including a desired signalling portion having a distinct time period of vibration and an undesired portion hav ing no distinct time period of vibration, modulating the portions of the received effects having a distinct time period of vibration in different manners so that one of such portions cannot neutralize the other, opposing the received effects one against the other so as to neutralize the portions of the effects which do not have a distinct time period of vibration and detecting the resultant of the effects.

2. The method of receiving signals and eliminating disturbances in radio receiving systems which consists in receiving energy as two effects having substantially the same frequency and each including a desired signalling portion having a distinct time period of vibration and an undesired portion having no distinct time period of vibration, modulating the portion of one of the received effects, which has a distinct time period of vibration, at a certain frequency to differentiate it from the corresponding portion of the other effect, opposing the received effects one against the other so as to neutralize the portions of the effects which do not have a distinct time period of vibration, and detecting the resultant of the first-mentioned portions of the effects.

3. The method of receiving signals and eliminating disturbances in radio receiving systems which consists in receiving energy as two efiects having substantially the same frequency and each including a desired signalling portion and an undesired disturbing portion, modulating the signaling energy of one of the received effects at a different frequency from the signaling energy of the other effect so that the signaling energies of the efiects cannot neutralize each other, opposing the received effects one against the other, so as to cause the portions of the effects resulting from disturbances to neutralize each other, and detecting the resultant of the combined effects.

4. The method of receiving signals and eliminating disturbances in radio receiving @raiiseaae energy in the receiving circuits, means for opposing the differentiated received effects to neutralize disturbances, and means for detecting the resultant of the combined effects.

8. A radio receiver for eliminating disturbances comprising a pair of receiving circuits tuned to' substantially the same frequency, means for modulating the signaling energy in one only of the received effects at a certain frequency to differentiate it from the signaling energy in the other effect, means for opposing the differentiated received effects and means for detecting the systems which consists in receiving energy sultant of the combined effects. as effects having substantially the same he 9. A radio receiver for eliminating disquency and each including a desired slgnalt bances comprising a pair of receiving ling portion having a distinct time period of vibration and an undesired portion having no distinct time period of vibration, modulating the received effects at different frequencies adapted to produce beats of different frequencies with the signal frequency, opposing the receiving efiects one against the other so as to neutralize the undesired disturbing portions which do not have a distinct time period of vibration, and detecting the resultant of the combined effects.

5. The method of receiving signals and eliminating disturbances in radio receiving systems which consists in receiving energy as two effects having substantially the same frequency and each including a desired signalling portion having a distinct time period of vibration and an undesired portion having no distinct time period of vibration, modulating the signalling portions of the received effects at d'iflerent frequencies adapted to produce beats of different frequencies, at least one of said beats being superaudible, combining the beats to produce another beat, and detecting the resultant of the combined effects.

6. The method of receiving signals and eliminating disturbances in radio receiving systems which consists in receiving energy as two effects having substantially the same frequency and each including a desired signalling portion having a distinct time period of vibration and an undesired portion having no distinct time period of vibration, modulating the signaling portions of the received effects which have a distinct time period of vibration, at different frequencies adapted to produce superaudible beats with the signal frequency, opposing the modulated received effects one against the other so as to neutralize the'undesired disturbing portions which do not have a distinct time period of vibration and to produce an audible beat, and detecting the audible beat.

7. A receiver for eliminating disturbances comprising a pair of receiving circuits tuned to substantially the same frequency, means for differently modulating the signaling circuits tuned to substantially the same frequency, means for modulating the portions of the received effects, which have a distinct time period of vibration, at different frequencies, means for opposing the differentiated received effects in such a manner as to neutralize the portions of the received effects which do not have a distinct time period of vibration, and means for detecting the resultant of the combined effects.

10. A radio receiver for eliminating disturbances comprising a pair of receiving circuits tuned to substantially the same frequency, means for modulating the signaling energies of the received effects at different frequencies adapted to produce beats of difierent frequencies with the signal frequency, means for opposing the differentiated received effects and means for detecting the resultant of the combined effects.

11. A radio receiver for eliminating disturbances comprising a pair of receiving circuits tuned to substantially the same frequency, means for superimposing different frequencies upon the: receiving systems to produce beats of different frequencies one of which is superaudible, means for opposing the resultant modulated effects to pro duce another beat and means for detecting the resultant of the combined effects.

12. A radio receiver for eliminating disturbances comprising a pair of receiving circuits tuned to substantially the same frequency, means for modulating the signaling energies of the received effects to produce a pair of superaudible beats of different frequencies, means for opposing the difierentiated received effects to neutralize disturbances which do not have a distinct time 7 period of vibration and to produce an audible beat between the first-mentioned beats and means for detecting the resultant of the combined effects.

13. A radio receiving system for eliminat ing disturbances comprising sin le antennai and a pair of receiving cirbmt's associ'ated therewith, said receiving circuits being tuned u.

In witness whereof I hereunto set my hand in the presence of two witnesses.

DR. ALEXANDER MEISSNER.

Witnesses MAX ABRAHAMSOHN, ERNST WVILLsE. 

